While Magnetic Resonance Imaging commonly provides excellent contrast between pathology and normal tissues, paramagentic substances such as Gadolinium have been shown to "enhance" lesions, and improve the detectibility, delineation, and differentiation from adjacent tissues on MRI scans. The DRD/NINCDS and NICHD have been involved in a study conducted by Berlex Laboratories, Inc. assessing the safety and diagnostic utility of this investigation of contrast medium, Gadolinium DTPA/Dimeglumine, in patients with tumors of the pituitary and acoustic neuromas. In 1985, Gadolinium DTPA/Dimeglumine underwent phase 2 trials at the NIH at which time 13 patients received this contrast agent with a variety of CNS tumors. These studies showed improved visualization of tumor/femur boundaries in a majority of cases. Additionally, we also began the examination of patients with pituitary microadenomas, with Cushing's syndrome and acoustic neuromas. To date we have scanned 16 patients with pituitary microadenomas. Gadolinium DTPA/Dimeglumine enhancement has been shown to be of benefit in delineating the microadenoma from the normal pituitary which has in the past eluded standard radiological techniques. We plan to continue further collaboration with Berlex, including the studies focusing on specific pituitary tumors including patients with prolactinomas, Cushing's disease and acromegaly.